1. Field Of The Invention
The present invention relates to a device for establishing communication between the interior and exterior of an airtight endoscope.
2. Description Of The Related Art
Two known devices for establishing communication between the interior and exterior of an endoscope are described in Japanese Utility Model Publication HEI No. 1-12802 and Japanese Utility Model Laid-Open Publication SHO No. 59-19105. The device disclosed in the first publication has a communicating valve provided in the outer wall portion of an endoscope in such a way that a valve body is normally pressed against a valve seat by a biasing device to isolate the interior of the endoscope from its exterior. When the valve body is disengaged from the valve seat against the urging force of the biasing device, communication is established between the interior and exterior of the endoscope. The device disclosed in the second publication has an air permeable but water impermeable porous member provided in the interior of an endoscope in such a way that it blocks the channel of communication between the interior and exterior of the endoscope.
These devices, however, have limitations. The first device, which has the communicating valve, tends to become unhygienic since fluids getting into the valve cannot easily be purged. The second device, which has the porous member provided in the interior of the endoscope, is unreliable because the operator is unable to check for the breakage of the porous member and, therefore, its deterioration will progress unnoticed until water gets into the endoscope when it is washed.